These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
In Normal risk, getting someone out of Australia will take a while, even with massive numbers on your side, mostly due to how the dice roll.
In Capital risk, crafty players will place their capitals in places with only one or two chokepoints to them. And then some jerk will put his in Australia.
Even with some of the mission cards, it's possible for two people to draw a card requiring that certain continents be held by them, and both of them need the same continent. This is frequently Asia. Occasionally, someone will end up drawing a card that requires Australia, and if they don't already have it...
Largely averted in the Lord of the Rings trilogy edition, since the game ends when the Ring is thrown into Mount Doom. If it lands on Mount Doom and keeps getting stalled by bad die rolls, however, you'll have a massive free-for-all with everyone attacking everything, hoping that theirs will be the last turn.
It's Easy, so It Sucks: It's commonly looked down on by "serious" wargamers both for being simple and for being entirely too luck-based with its dice-rolling mechanics.
Moreso when playing with the "Secret Mission" cards,note A set of 12 or 14 cards that give a specific goal, NOT to be confused with the separate "Secret Mission Risk" release since there is a set of them that read "Kill all of X army's units." While older versions explicitly stated that you must destroy the last unit to claim victory on that goal, it was later changed so that if the army is defeated by anyone and they do not fulfill their mission in the same instant, you win.